Multiple-section pump barrel



April 21, 1959 J. w. HATCH 2,883,246

' MULTIPLE-SECTION PUMP BARREL Filed June 15, 1955l JAMES H4 HATCH,

IN V EN TOR;

A Trop/ver.

United States Patent O MULTIPLE-SECTION PUMP BARREL James W. Hatch, Los Angeles, Calif., assignor to Monarch Engineering Corporation, Gardena, Calif., a corporation of California Application June 13, 1955, Serial No. 514,984

5 Claims. (Cl. 309-2) This invention relates to a barrel `construction for a pump and is directed specifically to the construction of a barrel for a pump of the character used in oil wells.

A pump for use at a subterranean location in an oil Well has a relatively long barrel, usually several feet in length, in which a reciprocating pump piston fits in a snug sliding manner. The problem is to provide such a pump barrel that has a precision bore throughout its length and is made of material to withstand the corrosive effects of oil well iluids. Conventional seamless tubing is not suitable for this purpose because its bore is not of accurate uniform dimension and because too often the tubing warps out of accurate longitudinal alignment. A further serious disadvantage is that conventional seamless tubing will not withstand the corrosive elfects of oil well uids.

It has been found that a practical procedure for fabricating such a pump barrel is, rst, to make up a number of barrel sections of suitable metal of suciently short length for accurate machining and then to assemble the sections end-to-end to form a multiple-section barrel. The individual sections may be made of suitable corrosion-resistant material such as brass, stainless steel, Monel metal, cast iron, and the like. The problem is how to assemble such short sections to form` along pump barrel.

The heretofore prevalent solution to this problem has been to enclose the accurately dimensioned short barrel sections in an overall tubular jacket. Such a jacket not onlyl embraces the series of cylindrical sections but also places the series of sections under longitudinal comprestion. Thus in a typical construction, the jacket has at least one screw-threaded end member for abutment against the end of a series of cylindrical sections. With the series of the cylindrical sections positioned end-to-end inside the jacket, an accurately dimensioned mandrel is inserted for accurate longitudinal alignment of the cylindrical sections and then the threaded end member of the jacket is tightened to place the series under longitudinal compression while the mandrel is still in place. In some instances, suitable material is introduced into the jacket to completely fill the annular space around the series of cylindrical sections to insure permanent alignment of the` sections. A metal or metal alloy having a low melting point may be employed for this purpose.

Certain disadvantages are inherent in this prior art use of a jacket to solve the problem of holding the short cylindrical sections in assembled positions. The addition of the jacket involves labor and material to increase the cost, and, moreover, the jacket greatly increases the outside vdiameter of the pump barrel.

The present invention solves this basic problem by directly interconnecting the short cylindrical sections with each other with such effectiveness that the necessity for a pump jacket is eliminated. The sections are bonded together end-to-end in a manner to produce in a unitary 2,883,246 Patented Apr. 21, 1959 pump barrel of strength comparable to a pump barrel of one piece construction.

The invention solves the problem by conically tapering the ends of the sections so that the adjacent ends mate or telescope together instead of merely abutting each other. The mating ends are then bonded together by low melting metal in a brazing procedure. Preferably the angle of taper of the mating joint surfaces relative to the axis of the pump barrel is relatively low, say on the order of 7-15.

The new pump barrel construction has important inherent structural advantages. In the lirst place, the cylindrical sections engage each other directly and in a positive manner to resist llexure of the multiple-section barrel even in the absence of bonding material. In the second place, by virtue of the relatively low angle of taper relative to the longitudinal axis of the pump barrel, forces tending to ex the pump barrel stress the bonding material in shear rather than in tension. Where bonded butt joints are used any forces that tend to Hex the pump barrel result in excessive concentrated tension of the bonding material. It is a well known fact that brazing materials offer greater resistance in shear than in tension. ln the third place, the tapered joints provide mating surfaces of relatively extensive area with consequent great reduction in the stressing in shear per unit area of the bonding material at each joint. By virtue of these inherent advantages, a pump barrel constructed as taught herein has a strength comparable to the strength of a one-piece pump barrel.

A further important advantage of the new construction is that the cylindrical sections tend to be selfaligning. Thus, with the tapered ends accurately dimensioned, merely positioning the cylindrical sections endto-end under moderate longitudinal compression tends to force each of the sections into accurate coaxial alignment. No such` tendency is provided by butt joints.

The features and advantages of the invention may be understood from the following detailed description` considered with the accompanying drawing. In the drawing which is to be regarded as merely illustrative:

Figure l is a view partly in section and partly in side elevation showing an oil well pump having a pump barrel` constructed in accord with the invention; and

Figure 2 is a longitudinal section of the pump barrel on an enlarged scale.

Figure l shows the construction of a typical oil well pump having a barrel, generally designated by numeral 10, and the usual piston 12 on the end of a string of sucker rod 14. The lower end of the barrel 10 is joined by screw threads to the usual valve section 15 incorporating a ball valve 16. The lower end of the valve section is connected to tubing 18 into which the oil llows from the underground source. The upper end of the pump barrel has the usual discharge ports 20.

The piston l2` is of tubular construction to provide a flow passage therethrough, the lower end of the flow passage being open to the interior of the barrel 10 and the upper end of the` llow` passage terminating in discharge ports 22 in the piston structure. The piston 12 includes a valve section 24 that incorporates a ball valve 25. Thus when the piston is reciprocated in the barrel, the two ball valves 16 and 25 cooperate to produce the pumping action.

In the preferred practice of the invention, the pump barrel 10 comprises a series of cylindrical sections which includes two opposite end sections 26 and a plurality of intermediate sections designated by the bracket 30. Each of the end sections 26 has internal screw threads 32. As hereto-fore stated the various sections of the barrel have mating conical ends. Thus each joint comprises telescoping conical surfaces and these surfaces are suitably bonded together preferably by a brazing process. Preferably, butnot necessarily, the two end sections 26 of the barrel are alike, the inner ends of both of the sections being either male or female. Such an arrangement affords substantial economy since it is necessary to make and stock only one type of end section. In such la construction the two ends of the series of intermediate sections 30 must also either both be male or both be female. Thus in the presently preferred embodiment of the invention, the inner ends of the two end sections 26 have inner conical surfaces 34 and the two ends of the plurality of intermediate sections 30 have outer conical surfaces 35 that mate with the conical surfaces 34.

' To make it possible for the end conical surfaces of the series of intermediate sections 30 to be of the same kind, at least one of the intermediate sections must have a male conical surface at one end and a female conical surface at the other end and at least one other of the intermediate sections must have conical surfaces at its opposite ends that are like each other. Thus the particular pump barrel shown in the drawings includes an intermediate cylindrical section 30a having -a previously mentioned male conical surface 35 at one end and a female conical surface 36 at the other end; and the pump barrel also includes a section 30b having a previously mentioned male conical surface 35 at one end and a second male conical surface 38 at the other end. The required length for the barrel 10 is achieved by adding one or more additional sections 30a als needed. In the present construction, only one additional section 30a is added, this section having a male conical surface 40 at one end and a female conical surface 42 at the other end. As heretofore stated, preferably the angle of taper of the various conical surfaces may be on the order of 7-15" relative to the axis of the barrel.v

In a typical practice of the invention, the various intermediate barrel sections are of a length of the order of magnitude of one foot. The individual cylindrical sections are preferably made of cast iron produced by a centrifugal casting operation. The castings are annealed, rough machined, heat-treated and then the bores Aof the castings are honed to precision. The finished multiple sections of the barrel are assembled in the order shown and are bonded together. In a typical procedure the sections are heated to approximately 1200" F. and are bonded together by silver solder. The resulting unified barrel structure has practically the same strength as a one-piece cylinder and will withstand all of the normal forces encountered in handling the barrel, in installing the pump in a well, and in operating the pump.

It is apparent that the invention has important advantages over prior art jacketed pump barrel constructions. There is a great 'saving in labor and material in the `elimination of the jacket. An additional advantage of at least equal importance is that the elimination of the jacket makes possible the use of a pump barrel of larger diameter in a given installation with consequent increased volumetric displacement of the pump. A further advantage is that in those instances where only one end of a pump barrel becomes seriously worn after a long period of service, it is a relatively simple and inexpensive matter to replace the end portion of the pump barrel. To do so, it is merely necessary to1 v thereto, for it' is susceptible to changes in form and detail within the scope of the appended claims.v

I claim:

1. A cylinder comprising: a plurality of coaxial cylindrical Asections positioned end to-end, said sections having oppositely tapered ends in the sense thatone end of each section has an outer tapered surface and the other end has an inner tapered surface, the adjacent ends of the successive sections being nested together and bonded together, lsaid plurality of sections further including an additional section both ends of which are tapered alike, one end of said additional section being nested with one end of said plurality of sections and bonded thereto to form therewith a unified cylinder assembly both ends of which are tapered alike, said plurality of sections further including two end cylinder sections bonded to the two ends respectively of said unified cylinder assembly to form a composite cylinder, each of said end cylinder sections having an outer end and an inner end with said two inner ends tapered alike, said inner ends being nested with and bonded to the tapered ends of said unified cylinder assembly.

p 2. A combination `as set forth in claim 1 in which each of the sections of said plurality of sections has a female` end and a male end; said additional section has two male ends; and said two end sections have inner female ends.

3. A combination as set forth in claim 1 in which the length of each of said plurality of sections is of the order of magnitude of one foot to facilitate precision finishing of the inner cylindrical surface throughout the whole length of the barrel.

4. A combination as set forth in claim 3 in which said sections are bonded together by metal having a substantially lower melting point than the material of the sections.

5. A combination as set forth in claim 4 in which the angle of taper of said nested ends relative to the axis of the barrel is of the order of magnitude of 7 -15 and in which the length of the individual sections is of the order of magnitude of one foot to facilitate precision finishing of the inner cylindrical surface throughout the whole length of the barrel.

References Cited in the iile of this patent UNITED STATES PATENTS France Feb. 23, 1955I 

